1
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Ham BS. Phase-controlled coherent photons for the quantum correlations in a delayed-choice quantum eraser scheme. Sci Rep 2024; 14:1752. [PMID: 38243015 PMCID: PMC10799079 DOI: 10.1038/s41598-024-52125-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2023] [Accepted: 01/14/2024] [Indexed: 01/21/2024] Open
Abstract
The delayed-choice quantum eraser has been intensively studied for the wave-particle duality of a single photon in an interferometric system over the last decades. Super-resolution has been studied over decades for quantum sensing to overcome the standard quantum limit. For the super-resolution, either quantum features of higher-order entangled photon pairs or classical features of phase-controlled coherent photons have been successfully demonstrated. Here, a method of classically excited super-resolution is presented for the phase-controlled coherent photons in a quarter-wave plate-modified quantum eraser scheme. To support the underlying physics of the super-resolution, nonlocal correlation is also presented with an additional frequency-polarization basis control via selective product-basis measurements.
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Affiliation(s)
- Byoung S Ham
- School of Electrical Engineering and Computer Science, Gwangju Institute of Science and Technology, 123 Chumdangwagi-ro, Buk-gu, Gwangju, 61005, South Korea.
- Qu-Lidar, 123 Chumdangwagi-ro, Buk-gu, Gwangju, 61005, South Korea.
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2
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Ham BS. Coherently driven quantum features using a linear optics-based polarization-basis control. Sci Rep 2023; 13:12925. [PMID: 37558762 PMCID: PMC10412634 DOI: 10.1038/s41598-023-40181-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2023] [Accepted: 08/06/2023] [Indexed: 08/11/2023] Open
Abstract
Quantum entanglement generation is generally known to be impossible by any classical means. According to Poisson statistics, coherent photons are not considered quantum particles due to the bunching phenomenon. Recently, a coherence approach has been applied for quantum correlations such as the Hong-Ou-Mandel (HOM) effect, Franson-type nonlocal correlation, and delayed-choice quantum eraser to understand the mysterious quantum features. In the coherence approach, the quantum correlation has been now understood as a direct result of selective measurements between product bases of phase-coherent photons. Especially in the HOM interpretation, it has been understood that a fixed sum-phase relation between paired photons is the bedrock of quantum entanglement. Here, a coherently excited HOM model is proposed, analyzed, and discussed for the fundamental physics of two-photon correlation using linear optics-based polarization-basis control. For this, polarization-frequency correlation in a Mach-Zehnder interferometer is coherently excited using synchronized acousto-optic modulators, where polarization-basis control is conducted via a selective measurement process of the heterodyne signals. Like quantum operator-based destructive interference in the HOM theory, a perfectly coherent analysis shows the same HOM effects of the paired coherent photons on a beam splitter, whereas individual output intensities are uniform.
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Affiliation(s)
- Byoung S Ham
- School of Electrical Engineering and Computer Science, Gwangju Institute of Science and Technology, 123 Chumdangwagi-ro, Buk-gu, Gwangju, 61005, South Korea.
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3
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Kim S, Ham BS. Revisiting self-interference in Young's double-slit experiments. Sci Rep 2023; 13:977. [PMID: 36653439 PMCID: PMC9849424 DOI: 10.1038/s41598-023-28264-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2022] [Accepted: 01/16/2023] [Indexed: 01/19/2023] Open
Abstract
Quantum superposition is the heart of quantum mechanics as mentioned by Dirac and Feynman. In an interferometric system, single photon self-interference has been intensively studied over the last several decades in both quantum and classical regimes. In Born rule tests, the Sorkin parameter indicates the maximum number of possible quantum superposition allowed to the input photons entering an interferometer, where multi-photon interference fringe is equivalent to that of a classical version by a laser. Here, an attenuated laser light in a quantum regime is investigated for self-interference in a Mach-Zehnder interferometer, and the results are compared with its classical version. The equivalent result supports the Born rule tests, where the classical interference originates in the superposition of individual single-photon self-interferences. This understanding sheds light on the fundamental physics of quantum features between bipartite systems.
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Affiliation(s)
- Sangbae Kim
- School of Electrical Engineering and Computer Science, Gwangju Institute of Science and Technology, 123 Chumdangwagi-Ro, Buk-Gu, Gwangju, 61005, South Korea
| | - Byoung S Ham
- School of Electrical Engineering and Computer Science, Gwangju Institute of Science and Technology, 123 Chumdangwagi-Ro, Buk-Gu, Gwangju, 61005, South Korea.
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4
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Ham BS. Randomness-based macroscopic Franson-type nonlocal correlation. Sci Rep 2022; 12:3759. [PMID: 35260682 PMCID: PMC8904538 DOI: 10.1038/s41598-022-07740-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2021] [Accepted: 02/14/2022] [Indexed: 11/30/2022] Open
Abstract
Franson-type nonlocal correlation is related to Bell inequality violation tests and has been applied for quantum key distributions based on time bin methods. Using unbalanced Mach–Zehnder interferometers, Franson correlation measurements result in an interference fringe, while local measurements do not. Here, randomness-based macroscopic Franson-type correlation is presented using polarization-based two-mode coherent photons, where the quantum correlation is tested by a Hong-Ou-Mandel scheme. Coherent photons are used to investigate the wave properties of this correlation. Without contradicting the wave-particle duality of quantum mechanics, the proposed method provides fundamental understanding of the quantum nature and opens the door to deterministic quantum information science.
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Affiliation(s)
- Byoung S Ham
- School of Electrical Engineering and Computer Science, Gwangju Institute of Science and Technology, 123 Chumdangwagi-ro, Buk-gu, Gwangju, 61005, South Korea.
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5
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Yin L, Hu Y, Zheng X. Measured uncertainty analysis of detection efficiency of single photon detectors with correlated photons calibration. APPLIED OPTICS 2022; 61:1316-1322. [PMID: 35201012 DOI: 10.1364/ao.446149] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/15/2021] [Accepted: 01/17/2022] [Indexed: 06/14/2023]
Abstract
Detection efficiency calibration based on correlated photons is a high precision calibration method at the single photon level. During the calibration process, measured time, photon count rate, and channel detection efficiency are important experimental parameters that affect the measured uncertainty of detection efficiency. This paper constructs simulation models of measured uncertainty with experimental parameters by the correlated photons method. Our experiment measures and predicts the uncertainty when parameters change. This research provides a quantitative basis for experimental parameter settings of calibration of single photon detectors using correlated photons technology.
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6
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The Franson Experiment as an Example of Spontaneous Breaking of Time-Translation Symmetry. Symmetry (Basel) 2022. [DOI: 10.3390/sym14020380] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
We describe an explicit statistical model of local hidden variables that reproduces the predictions of quantum mechanics for the ideal Franson experiment and sheds light on the physical mechanisms that might be involved in the actual experiment. The crux of our model is the spontaneous breaking of time-translation gauge symmetry by the hidden configurations of the pairs of photons locked in time and energy involved in the experiment, which acquire a non-zero geometric phase through certain cyclic transformations.
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7
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Ecker S, Sohr P, Bulla L, Huber M, Bohmann M, Ursin R. Experimental Single-Copy Entanglement Distillation. PHYSICAL REVIEW LETTERS 2021; 127:040506. [PMID: 34355974 DOI: 10.1103/physrevlett.127.040506] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/29/2021] [Accepted: 06/01/2021] [Indexed: 06/13/2023]
Abstract
The phenomenon of entanglement marks one of the furthest departures from classical physics and is indispensable for quantum information processing. Despite its fundamental importance, the distribution of entanglement over long distances through photons is unfortunately hindered by unavoidable decoherence effects. Entanglement distillation is a means of restoring the quality of such diluted entanglement by concentrating it into a pair of qubits. Conventionally, this would be done by distributing multiple photon pairs and distilling the entanglement into a single pair. Here, we turn around this paradigm by utilizing pairs of single photons entangled in multiple degrees of freedom. Specifically, we make use of the polarization and the energy-time domain of photons, both of which are extensively field tested. We experimentally chart the domain of distillable states and achieve relative fidelity gains up to 13.8%. Compared to the two-copy scheme, the distillation rate of our single-copy scheme is several orders of magnitude higher, paving the way towards high-capacity and noise-resilient quantum networks.
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Affiliation(s)
- Sebastian Ecker
- Institute for Quantum Optics and Quantum Information (IQOQI), Austrian Academy of Sciences, Boltzmanngasse 3, 1090 Vienna, Austria
- Vienna Center for Quantum Science and Technology (VCQ), Faculty of Physics, University of Vienna, Boltzmanngasse 5, 1090 Vienna, Austria
| | - Philipp Sohr
- Institute for Quantum Optics and Quantum Information (IQOQI), Austrian Academy of Sciences, Boltzmanngasse 3, 1090 Vienna, Austria
- Vienna Center for Quantum Science and Technology (VCQ), Faculty of Physics, University of Vienna, Boltzmanngasse 5, 1090 Vienna, Austria
| | - Lukas Bulla
- Institute for Quantum Optics and Quantum Information (IQOQI), Austrian Academy of Sciences, Boltzmanngasse 3, 1090 Vienna, Austria
- Vienna Center for Quantum Science and Technology (VCQ), Faculty of Physics, University of Vienna, Boltzmanngasse 5, 1090 Vienna, Austria
| | - Marcus Huber
- Institute for Quantum Optics and Quantum Information (IQOQI), Austrian Academy of Sciences, Boltzmanngasse 3, 1090 Vienna, Austria
- Institute for Atomic and Subatomic Physics, Vienna University of Technology, 1020 Vienna, Austria
| | - Martin Bohmann
- Institute for Quantum Optics and Quantum Information (IQOQI), Austrian Academy of Sciences, Boltzmanngasse 3, 1090 Vienna, Austria
- Vienna Center for Quantum Science and Technology (VCQ), Faculty of Physics, University of Vienna, Boltzmanngasse 5, 1090 Vienna, Austria
| | - Rupert Ursin
- Institute for Quantum Optics and Quantum Information (IQOQI), Austrian Academy of Sciences, Boltzmanngasse 3, 1090 Vienna, Austria
- Vienna Center for Quantum Science and Technology (VCQ), Faculty of Physics, University of Vienna, Boltzmanngasse 5, 1090 Vienna, Austria
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8
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Lum DJ, Mazurek MD, Mikhaylov A, Parzuchowski KM, Wilson RN, Jimenez R, Gerrits T, Stevens MJ, Cicerone MT, Camp CH. Witnessing the survival of time-energy entanglement through biological tissue and scattering media. BIOMEDICAL OPTICS EXPRESS 2021; 12:3658-3670. [PMID: 34221686 PMCID: PMC8221931 DOI: 10.1364/boe.423743] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/26/2021] [Revised: 05/19/2021] [Accepted: 05/20/2021] [Indexed: 06/13/2023]
Abstract
We demonstrate the preservation of the time-energy entanglement of near-IR photons through thick biological media (≤1.55 mm) and tissue (≤ 235 μm) at room temperature. Using a Franson-type interferometer, we demonstrate interferometric contrast of over 0.9 in skim milk, 2% milk, and chicken tissue. This work supports the many proposed opportunities for nonclassical light in biological imaging and analyses from sub-shot noise measurements to entanglement-enhanced fluorescence imaging, clearly indicating that the entanglement characteristics of photons can be maintained even after propagation through thick, turbid biological samples.
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Affiliation(s)
- Daniel J. Lum
- National Institute of Standards and Technology, Gaithersburg, MD 20899, USA
| | - Michael D. Mazurek
- Department of Physics, University of Colorado, Boulder CO 80309, USA
- National Institute of Standards and Technology, Boulder, CO 80305, USA
| | | | - Kristen M. Parzuchowski
- Department of Physics, University of Colorado, Boulder CO 80309, USA
- JILA, 440 UCB, University of Colorado, Boulder, CO 80309, USA
| | - Ryan N. Wilson
- Department of Physics, University of Colorado, Boulder CO 80309, USA
- JILA, 440 UCB, University of Colorado, Boulder, CO 80309, USA
| | - Ralph Jimenez
- JILA, 440 UCB, University of Colorado, Boulder, CO 80309, USA
- Department of Chemistry, 215 UCB, University of Colorado, Boulder, CO 80309, USA
| | - Thomas Gerrits
- National Institute of Standards and Technology, Gaithersburg, MD 20899, USA
| | - Martin J. Stevens
- National Institute of Standards and Technology, Boulder, CO 80305, USA
| | - Marcus T. Cicerone
- National Institute of Standards and Technology, Gaithersburg, MD 20899, USA
- School of Chemistry & Biochemistry, Georgia Institute of Technology, Atlanta, GA 30332, USA
| | - Charles H. Camp
- National Institute of Standards and Technology, Gaithersburg, MD 20899, USA
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9
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Abstract
A novel method of macroscopically entangled light-pair generation is presented for a quantum laser using randomness-based deterministic phase control of coherent light in a coupled Mach-Zehnder interferometer (MZI). Unlike the particle nature-based quantum correlation in conventional quantum mechanics, the wave nature of photons is applied for collective phase control of coherent fields, resulting in a deterministically controllable nonclassical phenomenon. For the proof of principle, the entanglement between output light fields from a coupled MZI is examined using the Hong-Ou-Mandel-type anticorrelation technique, where the anticorrelation is a direct evidence of the nonclassical features in an interferometric scheme. For the generation of random phase bases between two bipartite input coherent fields, a deterministic control of opposite frequency shifts results in phase sensitive anticorrelation, which is a macroscopic quantum feature.
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Affiliation(s)
- Byoung S Ham
- Center for Photon Information Processing, School of Electrical Engineering and Computer Science, Gwangju Institute of Science and Technology, 123 Chumdangwagi-ro, Buk-gu, Gwangju, 61005, South Korea.
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10
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Coherently controlled quantum features in a coupled interferometric scheme. Sci Rep 2021; 11:11188. [PMID: 34045595 PMCID: PMC8159952 DOI: 10.1038/s41598-021-90668-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2021] [Accepted: 05/11/2021] [Indexed: 12/03/2022] Open
Abstract
Over the last several decades, entangled photon pairs generated by spontaneous parametric down conversion processes in both second-order and third-order nonlinear optical materials have been intensively studied for various quantum features such as Bell inequality violation and anticorrelation. In an interferometric scheme, anticorrelation results from photon bunching based on randomness when entangled photon pairs coincidently impinge on a beam splitter. Compared with post-measurement-based probabilistic confirmation, a coherence version has been recently proposed using the wave nature of photons. Here, the origin of quantum features in a coupled interferometric scheme is investigated using pure coherence optics. In addition, a deterministic method of entangled photon-pair generation is proposed for on-demand coherence control of quantum processing.
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11
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Anwar A, Perumangatt C, Steinlechner F, Jennewein T, Ling A. Entangled photon-pair sources based on three-wave mixing in bulk crystals. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2021; 92:041101. [PMID: 34243479 DOI: 10.1063/5.0023103] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/26/2020] [Accepted: 03/01/2021] [Indexed: 06/13/2023]
Abstract
Entangled photon pairs are a critical resource in quantum communication protocols ranging from quantum key distribution to teleportation. The current workhorse technique for producing photon pairs is via spontaneous parametric down conversion (SPDC) in bulk nonlinear crystals. The increased prominence of quantum networks has led to a growing interest in deployable high performance entangled photon-pair sources. This manuscript provides a review of the state-of-the-art bulk-optics-based SPDC sources with continuous wave pump and discusses some of the main considerations when building for deployment.
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Affiliation(s)
- Ali Anwar
- Centre for Quantum Technologies, National University of Singapore, 3 Science Drive 2, S117543 Singapore, Singapore
| | - Chithrabhanu Perumangatt
- Centre for Quantum Technologies, National University of Singapore, 3 Science Drive 2, S117543 Singapore, Singapore
| | - Fabian Steinlechner
- Fraunhofer Institute for Applied Optics and Precision Engineering IOF, Albert-Einstein-Straße 7, 07745 Jena, Germany
| | - Thomas Jennewein
- Institute of Quantum Computing and Department of Physics and Astronomy, University of Waterloo, 200 University Ave. W, Waterloo, Ontario N2L 3G1, Canada
| | - Alexander Ling
- Centre for Quantum Technologies, National University of Singapore, 3 Science Drive 2, S117543 Singapore, Singapore
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12
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Elkus BS, Abdelsalam K, Fathpour S, Kumar P, Kanter GS. Quantum-correlated photon-pair generation via cascaded nonlinearity in an ultra-compact lithium-niobate nano-waveguide. OPTICS EXPRESS 2020; 28:39963-39975. [PMID: 33379534 DOI: 10.1364/oe.411575] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/05/2020] [Accepted: 12/05/2020] [Indexed: 06/12/2023]
Abstract
We generate quantum-correlated photon pairs using cascaded χ(2):χ(2) traveling-wave interactions for second-harmonic generation (SHG) and spontaneous parametric down-conversion (SPDC) in a single periodically-poled thin-film lithium-niobate (TFLN) waveguide. When pulse-pumped at 50 MHz, a 4-mm-long poled region with nearly 300%/Wcm2 SHG peak efficiency yields a generated photon-pair probability of 7±0.2 × 10-4 with corresponding coincidence-to-accidental ratio (CAR) of 13.6±0.7. The CAR is found to be limited by Stokes/anti-Stokes Raman-scattering noise generated primarily in the waveguide. A Raman peak of photon counts at 250 cm-1 Stokes shift from the fundamental-pump wavenumber suggests most of the noise that limits the CAR originates within the lithium niobate material of the waveguide.
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13
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14
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Ham BS. The origin of anticorrelation for photon bunching on a beam splitter. Sci Rep 2020; 10:7309. [PMID: 32355259 PMCID: PMC7193647 DOI: 10.1038/s41598-020-64441-2] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2019] [Accepted: 04/17/2020] [Indexed: 11/13/2022] Open
Abstract
The Copenhagen interpretation, in which the core concepts are Heisenberg's uncertainty principle and nonlocal EPR correlation, has been long discussed. Second-order anticorrelation in a beam splitter represents the origin of these phenomena and cannot be achieved classically. Here, the anticorrelation of nonclassicality in a beam splitter is interpreted using the concept of coherence. Unlike the common understanding of photons having a particle nature, anticorrelation is rooted in the wave nature of coherence optics, described by coherence optics, wherein quantum superposition between two input fields plays a key role. This interpretation may pose fundamental questions about the nature of nonclassicality and pave a road to coherence-based quantum information.
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Affiliation(s)
- Byoung S Ham
- Center for Photon Information Processing, School of Electrical Engineering and Computer Science, Gwangju Institute of Science and Technology, Gwangju, South Korea.
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15
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Zhao J, Ma C, Rüsing M, Mookherjea S. High Quality Entangled Photon Pair Generation in Periodically Poled Thin-Film Lithium Niobate Waveguides. PHYSICAL REVIEW LETTERS 2020; 124:163603. [PMID: 32383916 DOI: 10.1103/physrevlett.124.163603] [Citation(s) in RCA: 52] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/29/2020] [Accepted: 04/07/2020] [Indexed: 05/28/2023]
Abstract
A thin-film periodically poled lithium niobate waveguide was designed and fabricated which generates entangled photon pairs at telecommunications wavelengths with high coincidences-to-accidentals counts ratio CAR>67000, two-photon interference visibility V>99%, and heralded single-photon autocorrelation g_{H}^{(2)}(0)<0.025. Nondestructive in situ diagnostics were used to determine the poling quality in 3D. Megahertz rates of photon pairs were generated by less than a milliwatt of pump power, simplifying the pump requirements and dissipation compared to traditional spontaneous parametric down-conversion lithium niobate devices.
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Affiliation(s)
- Jie Zhao
- Department of Electrical and Computer Engineering, University of California, San Diego, La Jolla, California 92093-0407, USA
| | - Chaoxuan Ma
- Department of Electrical and Computer Engineering, University of California, San Diego, La Jolla, California 92093-0407, USA
| | - Michael Rüsing
- Department of Electrical and Computer Engineering, University of California, San Diego, La Jolla, California 92093-0407, USA
- TU Dresden, Institut für Angewandte Physik, Nöthnitzer Straße 61, 01187 Dresden, Germany
| | - Shayan Mookherjea
- Department of Electrical and Computer Engineering, University of California, San Diego, La Jolla, California 92093-0407, USA
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16
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Lugani J, Francis-Jones RJA, Boutari J, Walmsley IA. Spectrally pure single photons at telecommunications wavelengths using commercial birefringent optical fiber. OPTICS EXPRESS 2020; 28:5147-5163. [PMID: 32121741 DOI: 10.1364/oe.383704] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/19/2019] [Accepted: 01/25/2020] [Indexed: 06/10/2023]
Abstract
We report a bright and tunable source of spectrally pure heralded single photons in the telecom O-Band, based on cross-polarized four wave mixing in a commercial birefringent optical fiber. The source can achieve a purity of 85%, heralding efficiency of 30% and a coincidence-to-accidentals ratio of 108. Furthermore, through the measurements of joint spectral intensities, we find that the fiber is homogeneous over at least 45 centimeters and thus can potentially realize 4 sources that can produce identical quantum states of light. This paves the way for a cost-effective fiber-optic approach to implement multi-photon quantum optics experiments.
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17
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Zhang W, Fickler R, Giese E, Chen L, Boyd RW. Influence of pump coherence on the generation of position-momentum entanglement in optical parametric down-conversion. OPTICS EXPRESS 2019; 27:20745-20753. [PMID: 31510163 DOI: 10.1364/oe.27.020745] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/11/2019] [Accepted: 06/12/2019] [Indexed: 06/10/2023]
Abstract
We examine experimentally how the degree of position-momentum entanglement of photon pairs depends on the transverse coherence of the pump beam that excites them in a process of spontaneous parametric down-conversion. Using spatially incoherent light from a light-emitting diode, we obtain strong position correlation of the photons, but we find that transverse momentum correlation, and thus entanglement, is entirely absent. When we continuously vary the degree of spatial coherence on the pump beam, we observe the emergence of stronger momentum correlations and entanglement. We present theoretical arguments that explain our experimental results. Our results shed light on entanglement generation and can be applied to control entanglement for quantum information applications.
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18
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Ghafari F, Tischler N, Di Franco C, Thompson J, Gu M, Pryde GJ. Interfering trajectories in experimental quantum-enhanced stochastic simulation. Nat Commun 2019; 10:1630. [PMID: 30967533 PMCID: PMC6456595 DOI: 10.1038/s41467-019-08951-2] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2018] [Accepted: 02/04/2019] [Indexed: 12/02/2022] Open
Abstract
Simulations of stochastic processes play an important role in the quantitative sciences, enabling the characterisation of complex systems. Recent work has established a quantum advantage in stochastic simulation, leading to quantum devices that execute a simulation using less memory than possible by classical means. To realise this advantage it is essential that the memory register remains coherent, and coherently interacts with the processor, allowing the simulator to operate over many time steps. Here we report a multi-time-step experimental simulation of a stochastic process using less memory than the classical limit. A key feature of the photonic quantum information processor is that it creates a quantum superposition of all possible future trajectories that the system can evolve into. This superposition allows us to introduce, and demonstrate, the idea of comparing statistical futures of two classical processes via quantum interference. We demonstrate interference of two 16-dimensional quantum states, representing statistical futures of our process, with a visibility of 0.96 ± 0.02. Quantum devices should allow simulating stochastic processes using less memory than classical counterparts, but only if quantum coherence is maintained through multiple steps. Here, the authors demonstrate a coherence-preserving three-step stochastic simulation using photons.
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Affiliation(s)
- Farzad Ghafari
- Centre for Quantum Dynamics, Griffith University, Brisbane, QLD, 4111, Australia.
| | - Nora Tischler
- Centre for Quantum Dynamics, Griffith University, Brisbane, QLD, 4111, Australia
| | - Carlo Di Franco
- School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore, 639673, Singapore.,Complexity Institute, Nanyang Technological University, Singapore, 639673, Singapore
| | - Jayne Thompson
- Centre for Quantum Technologies, National University of Singapore, Singapore, 117543, Singapore
| | - Mile Gu
- School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore, 639673, Singapore. .,Complexity Institute, Nanyang Technological University, Singapore, 639673, Singapore. .,Centre for Quantum Technologies, National University of Singapore, Singapore, 117543, Singapore.
| | - Geoff J Pryde
- Centre for Quantum Dynamics, Griffith University, Brisbane, QLD, 4111, Australia.
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19
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Im DG, Kim Y, Kim YH. Periodic revival of frustrated two-photon creation via interference. OPTICS EXPRESS 2019; 27:7593-7601. [PMID: 30876321 DOI: 10.1364/oe.27.007593] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/18/2019] [Accepted: 02/20/2019] [Indexed: 06/09/2023]
Abstract
It has been known that suitably placed external mirrors can enhance and suppress emission of entangled photon pairs in spontaneous parametric down-conversion (SPDC), known as frustrated two-photon creation via interference. In this work, we report periodic revival of frustrated two-photon creation via interference with SPDC pumped by a continuous-wave (cw) multi-mode laser. As the mirrors are translated relative to the position of the SPDC source, the effect of frustrated two-photon creation via interference gradually dies off. However, as the mirrors are translated even further, the effect of frustrated two-photon creation via interference re-appears periodically. Our theoretical and numerical analyses show that this revival phenomenon is due to the nature of cw multi-mode pump laser. This work clearly demonstrates how the properties of the pump laser, in addition to suitably placed external mirrors, can be used to modify the process of spontaneous two-photon emission.
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20
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Vedovato F, Agnesi C, Tomasin M, Avesani M, Larsson JÅ, Vallone G, Villoresi P. Postselection-Loophole-Free Bell Violation with Genuine Time-Bin Entanglement. PHYSICAL REVIEW LETTERS 2018; 121:190401. [PMID: 30468593 DOI: 10.1103/physrevlett.121.190401] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/29/2018] [Revised: 09/11/2018] [Indexed: 06/09/2023]
Abstract
Entanglement is an invaluable resource for fundamental tests of physics and the implementation of quantum information protocols such as device-independent secure communications. In particular, time-bin entanglement is widely exploited to reach these purposes both in free space and optical fiber propagation, due to the robustness and simplicity of its implementation. However, all existing realizations of time-bin entanglement suffer from an intrinsic postselection loophole, which undermines their usefulness. Here, we report the first experimental violation of Bell's inequality with "genuine" time-bin entanglement, free of the postselection loophole. We introduced a novel function of the interferometers at the two measurement stations, that operate as fast synchronized optical switches. This scheme allowed us to obtain a postselection-loophole-free Bell violation of more than 9 standard deviations. Since our scheme is fully implementable using standard fiber-based components and is compatible with modern integrated photonics, our results pave the way for the distribution of genuine time-bin entanglement over long distances.
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Affiliation(s)
- Francesco Vedovato
- Dipartimento di Ingegneria dell'Informazione, Università di Padova, via Gradenigo 6B, 35131 Padova, Italy
- Centro di Ateneo di Studi e Attività Spaziali "G. Colombo", Università di Padova, via Venezia 15, 35131 Padova, Italy
| | - Costantino Agnesi
- Dipartimento di Ingegneria dell'Informazione, Università di Padova, via Gradenigo 6B, 35131 Padova, Italy
| | - Marco Tomasin
- Dipartimento di Ingegneria dell'Informazione, Università di Padova, via Gradenigo 6B, 35131 Padova, Italy
| | - Marco Avesani
- Dipartimento di Ingegneria dell'Informazione, Università di Padova, via Gradenigo 6B, 35131 Padova, Italy
| | - Jan-Åke Larsson
- Institutionen för systemteknik, Linköping Universitet, 581 83 Linköping, Sweden
| | - Giuseppe Vallone
- Dipartimento di Ingegneria dell'Informazione, Università di Padova, via Gradenigo 6B, 35131 Padova, Italy
- Istituto di Fotonica e Nanotecnologie, CNR, via Trasea 7, 35131 Padova, Italy
| | - Paolo Villoresi
- Dipartimento di Ingegneria dell'Informazione, Università di Padova, via Gradenigo 6B, 35131 Padova, Italy
- Istituto di Fotonica e Nanotecnologie, CNR, via Trasea 7, 35131 Padova, Italy
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21
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Ma C, Wang X, Mookherjea S. Photon-pair and heralded single photon generation initiated by a fraction of a 10 Gbps data stream. OPTICS EXPRESS 2018; 26:22904-22915. [PMID: 30184947 DOI: 10.1364/oe.26.022904] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/11/2018] [Accepted: 08/06/2018] [Indexed: 06/08/2023]
Abstract
A fraction of a classical 10 Gigabits-per-second, non-return-to-zero data stream at 1.55 micron wavelengths from a standard telecommunications optical transceiver was tapped and used to generate photon-pairs and heralded single photons using a silicon microring resonator at room temperature. These results show that there may be no need for a separate laser to generate high-quality photon pairs for quantum applications in a typical optical communications network.
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22
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MacLean JPW, Donohue JM, Resch KJ. Direct Characterization of Ultrafast Energy-Time Entangled Photon Pairs. PHYSICAL REVIEW LETTERS 2018; 120:053601. [PMID: 29481173 DOI: 10.1103/physrevlett.120.053601] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2017] [Indexed: 06/08/2023]
Abstract
Energy-time entangled photons are critical in many quantum optical phenomena and have emerged as important elements in quantum information protocols. Entanglement in this degree of freedom often manifests itself on ultrafast time scales, making it very difficult to detect, whether one employs direct or interferometric techniques, as photon-counting detectors have insufficient time resolution. Here, we implement ultrafast photon counters based on nonlinear interactions and strong femtosecond laser pulses to probe energy-time entanglement in this important regime. Using this technique and single-photon spectrometers, we characterize all the spectral and temporal correlations of two entangled photons with femtosecond resolution. This enables the witnessing of energy-time entanglement using uncertainty relations and the direct observation of nonlocal dispersion cancellation on ultrafast time scales. These techniques are essential to understand and control the energy-time degree of freedom of light for ultrafast quantum optics.
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Affiliation(s)
- Jean-Philippe W MacLean
- Institute for Quantum Computing, University of Waterloo, Waterloo, Ontario Canada, N2L 3G1
- Department of Physics & Astronomy, University of Waterloo, Waterloo, Ontario Canada, N2L 3G1
| | - John M Donohue
- Institute for Quantum Computing, University of Waterloo, Waterloo, Ontario Canada, N2L 3G1
- Department of Physics & Astronomy, University of Waterloo, Waterloo, Ontario Canada, N2L 3G1
- Integrated Quantum Optics, Applied Physics, University of Paderborn, 33098 Paderborn, Germany
| | - Kevin J Resch
- Institute for Quantum Computing, University of Waterloo, Waterloo, Ontario Canada, N2L 3G1
- Department of Physics & Astronomy, University of Waterloo, Waterloo, Ontario Canada, N2L 3G1
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23
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Ihn YS, Kim Y, Tamma V, Kim YH. Second-Order Temporal Interference with Thermal Light: Interference beyond the Coherence Time. PHYSICAL REVIEW LETTERS 2017; 119:263603. [PMID: 29328723 DOI: 10.1103/physrevlett.119.263603] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/18/2017] [Indexed: 06/07/2023]
Abstract
We report the observation of a counterintuitive phenomenon in multipath correlation interferometry with thermal light. The intensity correlation between the outputs of two unbalanced Mach-Zehnder interferometers (UMZIs) with two classically correlated beams of thermal light at the input exhibits genuine second-order interference with the visibility of 1/3. Surprisingly, the second-order interference does not degrade at all no matter how much the path length difference in each UMZI is increased beyond the coherence length of the thermal light. Moreover, the second-order interference is dependent on the difference of the UMZI phases. These results differ substantially from those of the entangled-photon Franson interferometer, which exhibits two-photon interference dependent on the sum of the UMZI phases and the interference vanishes as the path length difference in each UMZI exceeds the coherence length of the pump laser. Our work offers deeper insight into the interplay between interference and coherence in multiphoton interferometry.
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Affiliation(s)
- Yong Sup Ihn
- Department of Physics, Pohang University of Science and Technology (POSTECH), Pohang 37673, Korea
| | - Yosep Kim
- Department of Physics, Pohang University of Science and Technology (POSTECH), Pohang 37673, Korea
| | - Vincenzo Tamma
- Faculty of Science, SEES and Institute of Cosmology and Gravitation, University of Portsmouth, Portsmouth PO1 3QL, United Kingdom
| | - Yoon-Ho Kim
- Department of Physics, Pohang University of Science and Technology (POSTECH), Pohang 37673, Korea
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24
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He YQ, Ding D, Yan FL, Gao T. Scalable symmetry detector and its applications by using beam splitters and weak nonlinearities. Sci Rep 2017; 7:15356. [PMID: 29127363 PMCID: PMC5681639 DOI: 10.1038/s41598-017-15691-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2017] [Accepted: 10/31/2017] [Indexed: 11/17/2022] Open
Abstract
We describe a method to detect twin-beam multiphoton entanglement based on a beam splitter and weak nonlinearities. For the twin-beam four-photon entanglement, we explore a symmetry detector. It works not only for collecting two-pair entangled states directly from the spontaneous parametric down-conversion process, but also for generating them by cascading these symmetry detectors. Surprisingly, by calculating the iterative coefficient and the success probability we show that with a few iterations the desired two-pair can be obtained from a class of four-photon entangled states. We then generalize the symmetry detector to n-pair emissions and show that it is capable of determining the number of the pairs emitted indistinguishably from the spontaneous parametric down-conversion source, which may contribute to explore multipair entanglement with a large number of photons.
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Affiliation(s)
- Ying-Qiu He
- Department of Biomedical Engineering, Chengde Medical University, Chengde, 067000, China
| | - Dong Ding
- Department of Basic Curriculum, North China Institute of Science and Technology, Beijing, 101601, China.
| | - Feng-Li Yan
- College of Physics Science and Information Engineering, Hebei Normal University, Shijiazhuang, 050024, China.
| | - Ting Gao
- College of Mathematics and Information Science, Hebei Normal University, Shijiazhuang, 050024, China.
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25
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Polarization-entangled photon generation using partial spatially coherent pump beam. Sci Rep 2017; 7:12091. [PMID: 28935985 PMCID: PMC5608753 DOI: 10.1038/s41598-017-12376-6] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2017] [Accepted: 09/07/2017] [Indexed: 11/29/2022] Open
Abstract
The generation of two photon fields, to date, has been demonstrated utilizing a fully coherent pump beam. In this paper we demonstrate, the theoretical and experimental generation of polarization entangled single photon pairs by varying the spatial coherence of the pump beam. The effect of the pump beam spatial coherence on the visibility of a polarization-entangled single photon source is investigated. A comparison of the visibility measurements using a fully coherent and partially coherent pump beam is performed. It is shown that the partial coherence of the pump beam contributes to an increase in the visibility. The coherence properties of the beam are significant for free-space optical transmission in particular for long range free-space quantum communication.
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26
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Steinlechner F, Ecker S, Fink M, Liu B, Bavaresco J, Huber M, Scheidl T, Ursin R. Distribution of high-dimensional entanglement via an intra-city free-space link. Nat Commun 2017; 8:15971. [PMID: 28737168 PMCID: PMC5527279 DOI: 10.1038/ncomms15971] [Citation(s) in RCA: 89] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2016] [Accepted: 05/17/2017] [Indexed: 11/09/2022] Open
Abstract
Quantum entanglement is a fundamental resource in quantum information processing and its distribution between distant parties is a key challenge in quantum communications. Increasing the dimensionality of entanglement has been shown to improve robustness and channel capacities in secure quantum communications. Here we report on the distribution of genuine high-dimensional entanglement via a 1.2-km-long free-space link across Vienna. We exploit hyperentanglement, that is, simultaneous entanglement in polarization and energy-time bases, to encode quantum information, and observe high-visibility interference for successive correlation measurements in each degree of freedom. These visibilities impose lower bounds on entanglement in each subspace individually and certify four-dimensional entanglement for the hyperentangled system. The high-fidelity transmission of high-dimensional entanglement under real-world atmospheric link conditions represents an important step towards long-distance quantum communications with more complex quantum systems and the implementation of advanced quantum experiments with satellite links. Increasing the dimensionality of entangled states improves robustness and capacity of secure quantum communications, but it requires suitably modified setups. Here the authors report the distribution of high-dimensional polarization and energy-time entangled photons via a 1.2 km-long free-space link.
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Affiliation(s)
- Fabian Steinlechner
- Institute for Quantum Optics and Quantum Information (IQOQI), Austrian Academy of Sciences, Boltzmanngasse 3, A-1090 Vienna, Austria
| | - Sebastian Ecker
- Institute for Quantum Optics and Quantum Information (IQOQI), Austrian Academy of Sciences, Boltzmanngasse 3, A-1090 Vienna, Austria
| | - Matthias Fink
- Institute for Quantum Optics and Quantum Information (IQOQI), Austrian Academy of Sciences, Boltzmanngasse 3, A-1090 Vienna, Austria
| | - Bo Liu
- Institute for Quantum Optics and Quantum Information (IQOQI), Austrian Academy of Sciences, Boltzmanngasse 3, A-1090 Vienna, Austria.,School of Computer, NUDT, Changsha 410073, China
| | - Jessica Bavaresco
- Institute for Quantum Optics and Quantum Information (IQOQI), Austrian Academy of Sciences, Boltzmanngasse 3, A-1090 Vienna, Austria
| | - Marcus Huber
- Institute for Quantum Optics and Quantum Information (IQOQI), Austrian Academy of Sciences, Boltzmanngasse 3, A-1090 Vienna, Austria
| | - Thomas Scheidl
- Institute for Quantum Optics and Quantum Information (IQOQI), Austrian Academy of Sciences, Boltzmanngasse 3, A-1090 Vienna, Austria
| | - Rupert Ursin
- Institute for Quantum Optics and Quantum Information (IQOQI), Austrian Academy of Sciences, Boltzmanngasse 3, A-1090 Vienna, Austria.,Vienna Center for Quantum Science and Technology (VCQ), Faculty of Physics, University of Vienna, Boltzmanngasse 5, A-1090 Vienna, Austria
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27
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Agne S, Kauten T, Jin J, Meyer-Scott E, Salvail JZ, Hamel DR, Resch KJ, Weihs G, Jennewein T. Observation of Genuine Three-Photon Interference. PHYSICAL REVIEW LETTERS 2017; 118:153602. [PMID: 28452530 DOI: 10.1103/physrevlett.118.153602] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/17/2016] [Indexed: 06/07/2023]
Abstract
Multiparticle quantum interference is critical for our understanding and exploitation of quantum information, and for fundamental tests of quantum mechanics. A remarkable example of multi-partite correlations is exhibited by the Greenberger-Horne-Zeilinger (GHZ) state. In a GHZ state, three particles are correlated while no pairwise correlation is found. The manifestation of these strong correlations in an interferometric setting has been studied theoretically since 1990 but no three-photon GHZ interferometer has been realized experimentally. Here we demonstrate three-photon interference that does not originate from two-photon or single photon interference. We observe phase-dependent variation of three-photon coincidences with (92.7±4.6)% visibility in a generalized Franson interferometer using energy-time entangled photon triplets. The demonstration of these strong correlations in an interferometric setting provides new avenues for multiphoton interferometry, fundamental tests of quantum mechanics, and quantum information applications in higher dimensions.
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Affiliation(s)
- Sascha Agne
- Institute for Quantum Computing and Department of Physics and Astronomy, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada
| | - Thomas Kauten
- Institut für Experimentalphysik, Universität Innsbruck, Technikerstraße 25, 6020 Innsbruck, Austria
| | - Jeongwan Jin
- Institute for Quantum Computing and Department of Physics and Astronomy, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada
| | - Evan Meyer-Scott
- Institute for Quantum Computing and Department of Physics and Astronomy, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada
- Department of Physics, University of Paderborn, Warburger Straße 100, 33098 Paderborn, Germany
| | - Jeff Z Salvail
- Institute for Quantum Computing and Department of Physics and Astronomy, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada
| | - Deny R Hamel
- Département de Physique et d'Astronomie, Université de Moncton, Moncton, New Brunswick E1A 3E9, Canada
| | - Kevin J Resch
- Institute for Quantum Computing and Department of Physics and Astronomy, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada
| | - Gregor Weihs
- Institut für Experimentalphysik, Universität Innsbruck, Technikerstraße 25, 6020 Innsbruck, Austria
- Quantum Information Science Program, Canadian Institute for Advanced Research, Toronto, Ontario M5G 1Z8, Canada
| | - Thomas Jennewein
- Institute for Quantum Computing and Department of Physics and Astronomy, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada
- Quantum Information Science Program, Canadian Institute for Advanced Research, Toronto, Ontario M5G 1Z8, Canada
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28
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Laussy FP. Quantum optics: A new way to correlate photons. NATURE MATERIALS 2017; 16:398-399. [PMID: 28352096 DOI: 10.1038/nmat4884] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Affiliation(s)
- Fabrice P Laussy
- Faculty of Science and Engineering, University of Wolverhampton, Wulfruna Street, Wolverhampton WV1 1LY, UK, and the Russian Quantum Center, Novaya 100, 143025 Skolkovo, Moscow Region, Russia
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29
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Donohue JM, Mastrovich M, Resch KJ. Spectrally Engineering Photonic Entanglement with a Time Lens. PHYSICAL REVIEW LETTERS 2016; 117:243602. [PMID: 28009176 DOI: 10.1103/physrevlett.117.243602] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/19/2016] [Indexed: 06/06/2023]
Abstract
A time lens, which can be used to reshape the spectral and temporal properties of light, requires the ultrafast manipulation of optical signals and presents a significant challenge for single-photon application. In this work, we construct a time lens based on dispersion and sum-frequency generation to spectrally engineer single photons from an entangled pair. The strong frequency anticorrelations between photons produced from spontaneous parametric down-conversion are converted to positive correlations after the time lens, consistent with a negative-magnification system. The temporal imaging of single photons enables new techniques for time-frequency quantum state engineering.
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Affiliation(s)
- J M Donohue
- Institute for Quantum Computing and Department of Physics and Astronomy, University of Waterloo, Waterloo, Ontario, Canada N2L 3G1
| | - M Mastrovich
- Institute for Quantum Computing and Department of Physics and Astronomy, University of Waterloo, Waterloo, Ontario, Canada N2L 3G1
- Department of Physics, Harvey Mudd College, Claremont, California 91711, USA
| | - K J Resch
- Institute for Quantum Computing and Department of Physics and Astronomy, University of Waterloo, Waterloo, Ontario, Canada N2L 3G1
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30
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Thomas A, Van Camp M, Minaeva O, Simon D, Sergienko AV. Spectrally engineered broadband photon source for two-photon quantum interferometry. OPTICS EXPRESS 2016; 24:24947-24958. [PMID: 27828435 DOI: 10.1364/oe.24.024947] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
We present a new approach to engineering broadband sources of entangled photon pairs for quantum interferometry. The source is based on quasi-phase-matched spontaneous parametric down conversion in a titanium diffused periodically poled lithium niobate waveguide with a strongly-chirped poling period. The proposed non-standard asymmetric poling mitigates phase distortions associated with the process of chirping. Asymmetric poling significantly broadens the entangled source bandwidth while preserving high visibility quantum interferometric sensing.
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31
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Abstract
Einstein was wrong with his 1927 Solvay Conference claim that quantum mechanics is incomplete and incapable of describing diffraction of single particles. However, the Einstein-Podolsky-Rosen paradox of entangled pairs of particles remains lurking with its 'spooky action at a distance'. In molecules quantum entanglement can be viewed as basis of both chemical bonding and excitonic states. The latter are important in many biophysical contexts and involve coupling between subsystems in which virtual excitations lead to eigenstates of the total Hamiltonian, but not for the separate subsystems. The author questions whether atomic or photonic systems may be probed to prove that particles or photons may stay entangled over large distances and display the immediate communication with each other that so concerned Einstein. A dissociating hydrogen molecule is taken as a model of a zero-spin entangled system whose angular momenta are in principle possible to probe for this purpose. In practice, however, spins randomize as a result of interactions with surrounding fields and matter. Similarly, no experiment seems yet to provide unambiguous evidence of remaining entanglement between single photons at large separations in absence of mutual interaction, or about immediate (superluminal) communication. This forces us to reflect again on what Einstein really had in mind with the paradox, viz. a probabilistic interpretation of a wave function for an ensemble of identically prepared states, rather than as a statement about single particles. Such a prepared state of many particles would lack properties of quantum entanglement that make it so special, including the uncertainty upon which safe quantum communication is assumed to rest. An example is Zewail's experiment showing visible resonance in the dissociation of a coherently vibrating ensemble of NaI molecules apparently violating the uncertainty principle. Einstein was wrong about diffracting single photons where space-like anti-bunching observations have proven recently their non-local character and how observation in one point can remotely affect the outcome in other points. By contrast, long range photon entanglement with immediate, superluminal response is still an elusive, possibly partly misunderstood issue. The author proposes that photons may entangle over large distances only if some interaction exists via fields that cannot propagate faster than the speed of light. An experiment to settle this 'interaction hypothesis' is suggested.
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32
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Kumar R, Savanier M, Ong JR, Mookherjea S. Entanglement measurement of a coupled silicon microring photon pair source. OPTICS EXPRESS 2015; 23:19318-19327. [PMID: 26367592 DOI: 10.1364/oe.23.019318] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Using two-photon (Franson) interferometry, we measure the entanglement of photon pairs generated from an optically-pumped silicon photonic device consisting of a few coupled microring resonators. The pair-source chip operates at room temperature, and the InGaAs single-photon avalanche detectors (SPADs) are thermo-electrically cooled to 234K. Such a device can be integrated with other components for practical entangled photon-pair generation at telecommunications wavelengths.
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33
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Xing X, Feizpour A, Hayat A, Steinberg AM. Experimental demonstration of a flexible time-domain quantum channel. OPTICS EXPRESS 2014; 22:25128-25136. [PMID: 25401545 DOI: 10.1364/oe.22.025128] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
We present an experimental realization of a flexible quantum channel where the Hilbert space dimensionality can be controlled electronically. Using electro-optical modulators (EOM) and narrow-band optical filters, quantum information is encoded and decoded in the temporal degrees of freedom of photons from a long-coherence-time single-photon source. Our results demonstrate the feasibility of a generic scheme for encoding and transmitting multidimensional quantum information over the existing fiber-optical telecommunications infrastructure.
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34
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Kwon O, Park KK, Ra YS, Kim YS, Kim YH. Time-bin entangled photon pairs from spontaneous parametric down-conversion pumped by a cw multi-mode diode laser. OPTICS EXPRESS 2013; 21:25492-25500. [PMID: 24150388 DOI: 10.1364/oe.21.025492] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Generation of time-bin entangled photon pairs requires the use of the Franson interferometer which consists of two spatially separated unbalanced Mach-Zehnder interferometers through which the signal and idler photons from spontaneous parametric down-conversion (SPDC) are made to transmit individually. There have been two SPDC pumping regimes where the scheme works: the narrowband regime and the double-pulse regime. In the narrowband regime, the SPDC process is pumped by a narrowband cw laser with the coherence length much longer than the path length difference of the Franson interferometer. In the double-pulse regime, the longitudinal separation between the pulse pair is made equal to the path length difference of the Franson interferometer. In this paper, we propose another regime by which the generation of time-bin entanglement is possible and demonstrate the scheme experimentally. In our scheme, differently from the previous approaches, the SPDC process is pumped by a cw multi-mode (i.e., short coherence length) laser and makes use of the coherence revival property of such a laser. The high-visibility two-photon Franson interference demonstrates clearly that high-quality time-bin entanglement source can be developed using inexpensive cw multi-mode diode lasers for various quantum communication applications.
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35
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Ghalbouni J, Agha I, Frey R, Diamanti E, Zaquine I. Experimental wavelength-division-multiplexed photon-pair distribution. OPTICS LETTERS 2013; 38:34-36. [PMID: 23282829 DOI: 10.1364/ol.38.000034] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
We have experimentally implemented the distribution of photon pairs produced by spontaneous parametric downconversion through telecom dense-wavelength-division-multiplexing filters. Using the measured counts and coincidences between symmetric channels, we evaluate the maximum fringe visibility that can be obtained with polarization-entangled photons and compare different filter technologies.
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Affiliation(s)
- Joe Ghalbouni
- Institut Télécom/Télécom Paristech, CNRS-LTCI 46 rue Barrault, Paris 75013, France
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36
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Fickler R, Lapkiewicz R, Plick WN, Krenn M, Schaeff C, Ramelow S, Zeilinger A. Quantum Entanglement of High Angular Momenta. Science 2012; 338:640-3. [DOI: 10.1126/science.1227193] [Citation(s) in RCA: 514] [Impact Index Per Article: 42.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Affiliation(s)
- Robert Fickler
- Quantum Optics, Quantum Nanophysics, Quantum Information, University of Vienna, Vienna A-1090, Austria
- Institute for Quantum Optics and Quantum Information, Austrian Academy of Science, Vienna A-1090, Austria
| | - Radek Lapkiewicz
- Quantum Optics, Quantum Nanophysics, Quantum Information, University of Vienna, Vienna A-1090, Austria
- Institute for Quantum Optics and Quantum Information, Austrian Academy of Science, Vienna A-1090, Austria
| | - William N. Plick
- Quantum Optics, Quantum Nanophysics, Quantum Information, University of Vienna, Vienna A-1090, Austria
- Institute for Quantum Optics and Quantum Information, Austrian Academy of Science, Vienna A-1090, Austria
| | - Mario Krenn
- Quantum Optics, Quantum Nanophysics, Quantum Information, University of Vienna, Vienna A-1090, Austria
- Institute for Quantum Optics and Quantum Information, Austrian Academy of Science, Vienna A-1090, Austria
| | - Christoph Schaeff
- Quantum Optics, Quantum Nanophysics, Quantum Information, University of Vienna, Vienna A-1090, Austria
- Institute for Quantum Optics and Quantum Information, Austrian Academy of Science, Vienna A-1090, Austria
| | - Sven Ramelow
- Quantum Optics, Quantum Nanophysics, Quantum Information, University of Vienna, Vienna A-1090, Austria
- Institute for Quantum Optics and Quantum Information, Austrian Academy of Science, Vienna A-1090, Austria
| | - Anton Zeilinger
- Quantum Optics, Quantum Nanophysics, Quantum Information, University of Vienna, Vienna A-1090, Austria
- Institute for Quantum Optics and Quantum Information, Austrian Academy of Science, Vienna A-1090, Austria
- Vienna Center for Quantum Science and Technology, Faculty of Physics, University of Vienna, Vienna A-1090, Austria
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37
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Leach J, Jack B, Romero J, Jha AK, Yao AM, Franke-Arnold S, Ireland DG, Boyd RW, Barnett SM, Padgett MJ. Quantum Correlations in Optical Angle–Orbital Angular Momentum Variables. Science 2010; 329:662-5. [DOI: 10.1126/science.1190523] [Citation(s) in RCA: 423] [Impact Index Per Article: 30.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Affiliation(s)
- Jonathan Leach
- Department of Physics and Astronomy, Scottish Universities Physics Alliance (SUPA), University of Glasgow, Glasgow, G12 8QQ, UK
| | - Barry Jack
- Department of Physics and Astronomy, Scottish Universities Physics Alliance (SUPA), University of Glasgow, Glasgow, G12 8QQ, UK
| | - Jacqui Romero
- Department of Physics and Astronomy, Scottish Universities Physics Alliance (SUPA), University of Glasgow, Glasgow, G12 8QQ, UK
| | - Anand K. Jha
- Institute of Optics, University of Rochester, Rochester, NY 14627, USA
| | - Alison M. Yao
- Department of Physics, SUPA, University of Strathclyde, Glasgow, G4 0NG, UK
| | - Sonja Franke-Arnold
- Department of Physics and Astronomy, Scottish Universities Physics Alliance (SUPA), University of Glasgow, Glasgow, G12 8QQ, UK
| | - David G. Ireland
- Department of Physics and Astronomy, Scottish Universities Physics Alliance (SUPA), University of Glasgow, Glasgow, G12 8QQ, UK
| | - Robert W. Boyd
- Institute of Optics, University of Rochester, Rochester, NY 14627, USA
| | - Stephen M. Barnett
- Department of Physics, SUPA, University of Strathclyde, Glasgow, G4 0NG, UK
| | - Miles J. Padgett
- Department of Physics and Astronomy, Scottish Universities Physics Alliance (SUPA), University of Glasgow, Glasgow, G12 8QQ, UK
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38
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Smith BJ, Mahou P, Cohen O, Lundeen JS, Walmsley IA. Photon pair generation in birefringent optical fibers. OPTICS EXPRESS 2009; 17:23589-23602. [PMID: 20052068 DOI: 10.1364/oe.17.023589] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
We study both experimentally and theoretically the generation of photon pairs by spontaneous four-wave mixing (SFWM) in standard birefringent optical fibers. The ability to produce a range of two-photon spectral states, from highly correlated (entangled) to completely factorable, by means of cross-polarized birefringent phase matching, is explored. A simple model is developed to predict the spectral state of the photon pair which shows how this can be adjusted by choosing the appropriate pump bandwidth, fiber length and birefringence. Spontaneous Raman scattering is modeled to determine the tradeoff between SFWM and background Raman noise, and the predicted results are shown to agree with experimental data.
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Affiliation(s)
- Brian J Smith
- Centre for Quantum Technologies, National University of Singapore 3 Science Drive 2, 117543 Singapore, Singapore.
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Ramelow S, Ratschbacher L, Fedrizzi A, Langford NK, Zeilinger A. Discrete tunable color entanglement. PHYSICAL REVIEW LETTERS 2009; 103:253601. [PMID: 20366255 DOI: 10.1103/physrevlett.103.253601] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/30/2009] [Indexed: 05/29/2023]
Abstract
Although frequency multiplexing of information has revolutionized the field of classical communications, the color degree of freedom (DOF) has been used relatively little for quantum applications. We experimentally demonstrate a new hybrid quantum gate that transfers polarization entanglement of nondegenerate photons onto the color DOF. We create, for the first time, high-quality, discretely color-entangled states (with energy band gap up to 8.4 THz) without any spectrally selective filtering, and unambiguously verify and quantify the amount of entanglement (tangle, 0.611 +/- 0.009) by reconstructing a restricted density matrix; we generate a range of maximally entangled states, including a set of mutually unbiased bases for an encoded qubit space. The technique can be generalized to transfer polarization entanglement onto other photonic DOFs, like orbital angular momentum.
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Affiliation(s)
- S Ramelow
- Institute for Quantum Optics and Quantum Information, Austrian Academy of Sciences, Boltzmanngasse 3, A-1090 Vienna, Austria
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40
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Hayat A, Ginzburg P, Orenstein M. Photon energy entanglement characterization by electronic transition interference. OPTICS EXPRESS 2009; 17:21280-21288. [PMID: 19997367 DOI: 10.1364/oe.17.021280] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
We propose photon energy qubits and schemes for photon energy entanglement characterization. Bell inequality violation for energy qubits and complete Bell state analysis are demonstrated theoretically. Photon energy superposition state detection is performed by a two-photon absorption interferometer based on electron transition path interference. The scheme can be realized at room-temperature by two-level systems and semiconductor devices.
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Affiliation(s)
- Alex Hayat
- Department of Electrical Engineering, Technion, Haifa 32000, Israel.
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41
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Takesue H, Noguchi Y. Implementation of quantum state tomography for time-bin entangled photon pairs. OPTICS EXPRESS 2009; 17:10976-10989. [PMID: 19550497 DOI: 10.1364/oe.17.010976] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Quantum state tomography (QST) is an important method for evaluating the quality of entangled photon pairs, and has been widely used to measure polarization entanglement. However, QST has not been applied to time-bin entanglement, which is a type of entanglement suitable for fiber transmission. In this paper, we clarify the way to implement QST on time-bin entangled photon pairs using a 1-bit delayed interferometer. We also provide experimental results for a demonstration of QST for time-bin entangled photon pairs generated using spontaneous four-wave mixing in a dispersion shifted fiber.
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Affiliation(s)
- Hiroki Takesue
- NTT Basic Research Laboratories, NTT Corporation, Atsugi, Japan.
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42
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Leach J, Jack B, Romero J, Ritsch-Marte M, Boyd RW, Jha AK, Barnett SM, Franke-Arnold S, Padgett MJ. Violation of a Bell inequality in two-dimensional orbital angular momentum state-spaces. OPTICS EXPRESS 2009; 17:8287-93. [PMID: 19434161 DOI: 10.1364/oe.17.008287] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
We observe entanglement between photons in controlled super-position states of orbital angular momentum (OAM). By drawing a direct analogy between OAM and polarization states of light, we demonstrate the entangled nature of high order OAM states generated by spontaneous downconversion through violation of a suitable Clauser Horne Shimony Holt (CHSH)-Bell inequality. We demonstrate this violation in a number of two-dimensional subspaces of the higher dimensional OAM Hilbert space.
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Affiliation(s)
- J Leach
- Department of Physics and Astronomy, SUPA, University of Glasgow, Glasgow, UK.
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43
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Cabello A, Rossi A, Vallone G, De Martini F, Mataloni P. Proposed bell experiment with genuine energy-time entanglement. PHYSICAL REVIEW LETTERS 2009; 102:040401. [PMID: 19257405 DOI: 10.1103/physrevlett.102.040401] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/31/2008] [Indexed: 05/27/2023]
Abstract
Franson's Bell experiment with energy-time entanglement [Phys. Rev. Lett. 62, 2205 (1989)10.1103/PhysRevLett.62.2205] does not rule out all local hidden variable models. This defect can be exploited to compromise the security of Bell inequality-based quantum cryptography. We introduce a novel Bell experiment using genuine energy-time entanglement, based on a novel interferometer, which rules out all local hidden variable models. The scheme is feasible with actual technology.
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Affiliation(s)
- Adán Cabello
- Departamento de Física Aplicada II, Universidad de Sevilla, E-41012 Sevilla, Spain.
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44
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Jha AK, Malik M, Boyd RW. Exploring energy-time entanglement using geometric phase. PHYSICAL REVIEW LETTERS 2008; 101:180405. [PMID: 18999801 DOI: 10.1103/physrevlett.101.180405] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/16/2008] [Indexed: 05/27/2023]
Abstract
Using the signal and idler photons produced by parametric down-conversion, we report an experimental observation of a violation of the Bell inequality for energy and time based purely on the geometric phases of the signal and idler photons. We thus show that energy-time entanglement between the signal and idler photons can be explored by means of their geometric phases. These results may have important practical implications for quantum information science by providing an additional means by which entanglement can be manipulated.
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Affiliation(s)
- Anand Kumar Jha
- The Institute of Optics, University of Rochester, Rochester, New York 14627, USA
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45
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Broadbent CJ, Camacho RM, Xin R, Howell JC. Preservation of energy-time entanglement in a slow light medium. PHYSICAL REVIEW LETTERS 2008; 100:133602. [PMID: 18517953 DOI: 10.1103/physrevlett.100.133602] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/05/2007] [Indexed: 05/26/2023]
Abstract
We demonstrate the preservation of entanglement of an energy-time entangled biphoton through a slow light medium. Using the D(1) and D(2) fine structure resonances of Rubidium, we delay one photon of the 1.5 THz biphoton by approximately 1.3 correlation lengths and measure the fourth order correlation fringes. After the group delay the fringe visibility is reduced from 97.0+/-4.4% to 80.0+/-4.8%, but is still sufficient to violate a Bell inequality. We show that temporal broadening is the primary mechanism for reducing the fringe visibility and that smaller bandwidths lead to greatly reduced broadening.
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Affiliation(s)
- Curtis J Broadbent
- Department of Physics and Astronomy, University of Rochester, Rochester, New York 14627, USA
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46
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SHIH YH, SERGIENKO AV, PITTMAN TB, STREKALOV DV, KLYSHKO DN. Two-Photon “Ghost” Image and Interference-Diffractiona. Ann N Y Acad Sci 2006. [DOI: 10.1111/j.1749-6632.1995.tb38962.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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47
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48
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49
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Law CK, Eberly JH. Analysis and interpretation of high transverse entanglement in optical parametric down conversion. PHYSICAL REVIEW LETTERS 2004; 92:127903. [PMID: 15089711 DOI: 10.1103/physrevlett.92.127903] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/30/2003] [Indexed: 05/24/2023]
Abstract
Quantum entanglement associated with transverse wave vectors of down conversion photons is investigated based on the Schmidt decomposition method. We show that transverse entanglement involves two variables: orbital angular momentum and transverse frequency. We show that in the monochromatic limit high values of entanglement are closely controlled by a single parameter resulting from the competition between (transverse) momentum conservation and longitudinal phase matching. We examine the features of the Schmidt eigenmodes, and indicate how entanglement can be enhanced by suitable mode selection methods.
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Affiliation(s)
- C K Law
- Department of Physics, The Chinese University of Hong Kong, Shatin, Hong Kong, China
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50
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Bovino FA, Castagnoli G, Degiovanni IP, Castelletto S. Experimental evidence for bounds on quantum correlations. PHYSICAL REVIEW LETTERS 2004; 92:060404. [PMID: 14995222 DOI: 10.1103/physrevlett.92.060404] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/13/2003] [Indexed: 05/24/2023]
Abstract
We implemented the experiment proposed by Cabello in the preceding Letter to test the bounds of quantum correlation. As expected from the theory we found that, for certain choices of local observables, Tsirelson's bound of the Clauser-Horne-Shimony-Holt inequality (2 x square root of 2) is not reached by any quantum states.
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Affiliation(s)
- F A Bovino
- Elsag spa, Via Puccini 2-16154 Genoa, Italy.
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